Bolt guard



1937- G. P. SCHIEHL 2,090,236

BOLT GUARD Filed Feb. 1, 1936 Big. 1. Big. ,9.

ATTORNEY.

Patented Aug. 17, 1937 E UNITE' STATES PATENT OFFIQE BOLT GUARD 6 Claims.

This invention relates to improvements in means for safeguarding doors which are provided with locks having spring pressed bolts, and relates more specifically to an improved bolt guard'which is adapted to be secured to the strike plate on the 'jamb of the door opening.

In recent'years there has been a great increase in the extent of petty thievery in office buildings, hotels and apartment houses. The usual spring pressed bolt ,with the bevelled :fface may be readily retracted by inserting a flat flexible instrumen't, such as a celluloid ruler, between the jamb and the door. In doors of the usual construction, the free vertical edge thereof is somewhat bevelled and when the door is closed there is normally a fair amount of space between this edge and the jamb, in order to prevent any obstruction in the opening and closing of the door iftheparts'have expanded under the influence of heat or otherwise.

Various types of spring pressed pivotally mounted members have been devised to prevent the insertion of the flexible member, but in most instances the skilled thief is actually aided rather than hinderedby such devices.

It is one of the principal objects of the pres- 1 ent invention to provide a simple and inexpensive device which may be readily secured to the lock strike and which will effectually prevent the surreptitiou's opening of the lock, unless the looking mechanism is itself picked. The device consists essentially or a plurality of coil compression springs" constructed in a certain fashion and secured'to" the strike plate in such a manner as to have a yielding engagement with the free verti'c'al'edge of the door when the latter is closed, the spring being so situated as to effectively catchany foreign member inserted as aforesaid.

Another object of the invention is the provision of a bolt guard which may be quickly attached to any conventional lock strike, the device being of sufficient simplicity as to require no servicing or attention.

In the drawing:

Fig. 1 is a side elevation of a conventional box strike showing the improved bolt guard in position thereon;

2 is a front elevation thereof, the View showing the bolt in section;

Fig.3 is a section taken on line 33 of Fig. 2; i Fig. 4 showsthe relation of the various spring elements to each other;

Fig. 5 isa front elevation of a conventional flat strike plate with the present invention secured thereto; and

Fig. 6 is a rear elevation thereof.

I have illustrated in the drawing a number of types of conventional lock strike plates in connection with which my invention may be employed. In Figs. 1, 2 and 3, there is illustrated a strike plate H! of the box variety, the plate being provided with a single rectangular bolt opening having upper and lower horizontal edges H and I2, respectively, and right and left vertical edges l3 and [4, respectively. The plate is further provided with screw'apertures It at each end thereof andan integrally formed bevelled bolt strike extension ll.

The instant invention, in its presently preferred form, consists essentially of two or more coil or other shaped compression springs which are carried'by the strike plate, the springs being of sufficient depth to normally engage the free vertical edge of the door, when the latter is in a closedpositionywith a fair degree of compression. The precise number of springs required in any given instance is dependent upon the shape and size of the opening. In applying the springs to the plate illustrated in Figs. 1, 2 and 3, apertures I9' and 2B are first drilled in the plate. These apertures are located approximately onequarter of an inch above and below the horizontal edges II and 12 of the bolt aperture and are slightly to the left of the left-hand vertical edge 14. The location of these two apertures is of considerable importance, since if they are not substantially in alignment with this vertical edge,

the spring members hereinafter described may possibly interfere with the action of the spring pressed bolt in extending itself to its outer limit.

After the apertures i9 and 2% have been drilled in the plate, apertures 22 and 23 are formed in the upper and lower horizontal walls 24 and 25,

respectively, of the box, these apertures being formed substantially in alignment with the previous apertures.

It will be noted in Fig. 2 that the bolt 2! is positioned substantially midway between the upper and lower vertical edges of the bolt aperture. In actual practice, however, the bolt may more closely approach either upper or lower edges of the bolt aperture depending upon the manner in which the door is hung or the accuracy of the template of the lock. The person seeking to retract the bolt by means of a thin flexible element normally employs one or the other of the horizontal edges of the bolt aperture as the fulcrum, which fulcrum in cooperation with the bevelled terminal of the bolt makes the task of retracting the bolt a relatively simple process. In order to destroy the effectiveness of these edges as a fulcrum, the upper and lower springs are necessarily positioned at a suitable distance above and below the edges. When the bolt 21 approaches the strike from the right, as shown in Fig. 2, it is essential that the upper spring, designated as 29, be wound in a clockwise direction and, in most instances, two turns of the spring is sufficient to provide the desired depth. The terminal 30 of the turn of the spring adjacent to the plate passes through the aperture [9 therein and to the rear of the plate where it is secured in the manner hereinafter described. It will be noted from. an examination of Figs. 2 and 3 that as the wire from which the spring 29 is formed emerges from the aperture I 9 to the front of the plate, it almost immediately begins to curve upwardly, since if a major portion of the spring lay below the aperture I9, the requisite protection could not be obtained. The opposite terminal 3| of the wire forming the spring 29 passes diagonally through the bolt aperture and the box, and through the aperture 23 in the lower wall 25 of the box. It is essential in this instance that the wire rather closely cling to the vertical edge l4 of the bolt aperture since if this wire were bowed upwardly, it would interfere with the free outward movement of the bolt.

The inner terminal 33 of the lower spring 34 passes through the aperture 20 at the lower end of the plate and the opposite terminal 35 of this spring also passes diagonally through the bolt aperture adjacent to the edge l4 and out through the aperture 22 in the upper wall 24 of the box. It will be noted that this terminal portion 35 of the spring likewise lies adjacent to the edge l4 and in close proximity to the portion 3| of the upper spring. It is essential that this Spring be wound in a counter-clockwise fashion.

The central spring 31 may be wound either clockwise or counter-clockwise and the upper terminal 38 passes out through the upper aperture l9, preferably to the left of the terminal 3| of the upper spring. The lower terminal 39 of the central spring passes through the lower aperture 20, also the-left of the terminal 35 of the lower spring.

Thus, at the upper end of the box, the wires 35, 3B and 38 meet just above the upper wall 24, which terminals are soldered together at 36. Likewise, the lower terminals 3l, 33 and. 39, meet adjacent to the lower surface of the lower wall 25, where they are likewise secured at 36'. It is not essential that these terminals, after being soldered to each other, be soldered to the box itself.

After the terminals have been secured in the foregoing manner, the wires 38 and 3| at the upper end of the plate may be secured together by afiixing a drop of solder at 4| thereto. Likewise, the wires 39 and 35 are secured together by the solder at 42 and the wires 35 and 3| inside the box are secured together by the solder at 43. It is important to providev a substantial web of solder at the points 4! and 42, the web extending towards the center spring, in order to prevent the insertion of an effective instrument under the center spring.

In the event that the bolt aperture is of greater length than that shown in Figs. 1, 2 and 3, the device can be provided with two or more intermediate springs. Thus it will be seen that when any foreign fiat element is inserted between the door and the jamb, its progress is instantly arrested by one of the springs.

' this character is to drill apertures 59 and 60 slightly above and below the horizontal edges 52 and 53, respectively, of the bolt aperture, the aperture being substantially in alignment with the vertical edge 55. The inner terminal 62 of the upper spring 63 passes through the aperture 59 and the opposite terminal 64 of the spring passes through the bolt aperture, adjacent to the left vertical edge 55 thereof; Likewise, the innor terminal 61 of the lower spring 68 passes through the lower aperture 60 and the opposite terminal 69 thereof passes diagonally through the bolt aperture adjacent to the edge 55. The opposite terminals 10 and ll of the intermediate spring 12 pass through the apertures 59 and 60 and the three terminals are secured together by a soldering or otherwise at the rear of the plate, as shown in Fig. 6. The terminals of the wires should be made to extend only a short distance beyond the inner face of the plate in order to give free acceptance of the strike into its template. :2.

ing means to yieldingly engage the door when the latter is in a closed position, said latter means comprising a plurality of spaced compression springsv secured to said plate.

2. 'A bolt guard including, in combination, a; strike plate having means to receive the bolt,

means positioned adjacent to said bolt receiving means to yieldingly engage the door when the latter is in a closed position, said latter means comprising a plurality of elements having interstices therein to receive the edge of a flat member inserted between the door and the jamb and thereby prevent the retraction of the bolt by said fiat member.

3. A guard for spring pressed bolts including;

in combination, a strike plate having a bolt re ceiving aperture and a smaller aperture above and below said bolt receiving aperture, saidtwo latter apertures being substantially in alignment with one vertical edge of the bolt rality of coil compression springs positioned adjacent to said vertical edge, at least one terminal of each of said springs passing through one of said smaller apertures and being secured at the rear of the plate.

4. In a device of the class described, the combination of a strike plate and a plurality of interconnected coil springs mounted thereon and adapted to engage a door when the latter is in a closed position, the individual coils of each aperture, a pluspring being sufiiciently spaced to form narrow interstices therebetween, which interstices are adapted to receive the edge of a flat member inserted between the door and the jamb and thereby prevent the retraction of the bolt by said flat member.

5. In combination with a strike plate having a bolt receiving aperture, means positioned along one vertical edge of the bolt receiving aperture for preventing the retraction of the bolt by the insertion of a flat, flexible member between the door and the jamb, said means comprising a plurality of coil springs mounted in spaced relation along said edge of the bolt receiving aperture, the individual turns of the springs being sufiiciently spaced to receive the edges of said flat member.

6. In combination with a strike plate having a bolt receiving aperture, means positioned along one vertical edge of the bolt receiving aperture for preventing the retraction of the bolt by the insertion of a fiat, flexible member between the door and the jamb, said means comprising a plurality of coil springs mounted in spaced relation along said edge of the bolt receiving aperture, the springs being so positioned as to engage the vertical edge of the door when in a closed position but not extending sufliciently from the plate as to be struck by the door while the latter is being closed.

GEORGE P. SCHIEHL. 

